Exercise metering devices have a long history in the prior art. For example, Kerwin U.S. Pat. No. 3,511,097 shows a bicycle-type exercise apparatus connected to electronic circuitry including current integrators for measuring the energy output of the bicycle apparatus and giving a continuous count indication of the amount of exercise. However, most people for whom exercise is prescribed or desired wish to have greater freedom in their choice of the exercise to be performed than is provided with such a stationary system. A similar device showing calories expended on an electronic readout also is disclosed in Barron U.S. Pat. No. 3,984,666. However, this system suffers from the same limitation as the Kerwin apparatus.
In an attempt to break away from the limitations of these prior art devices, it has been proposed to provide a magnetic accelerometer, such as shown in Tognola U.S. Pat. No. 3,129,347 which has a magnet as a moving part therein, to detect the amount of motion by the user. It has been further proposed to provide the housing of this accelerometer, shown for example in FIG. 1, with a mechanical switch such as a reed switch to determine when the movable magnet moves within proximity of the stationary magnet because of the force of the motion of the user. While this device is of interest as a basic concept, it is not a commercially practical system because the mechanical system for measuring magnet positioning is subject to inaccuracy caused by magnetic field variations and breakdown problems inherent in such mechanical structures.
It has also been proposed as an alternative means for detecting activity that a magnet be placed adjacent a pickup coil as shown in Bornmann U.S. Pat. No. 3,547,106. Such a position-detection pickup coil (which is also shown in the Tognola patent) is expensive to implement; its output signal requires substantial circuitry for processing, as shown in block form in FIG. 1 of the Bornmann patent, which includes a band pass filter, rectifier, trigger, multivibrator, timer and flip-flop.
Obviously, simplified position-detecting circuitry for the transducer to provide an accurate, reliable signal was necessary to provide a commercially feasible device. Further, the piror art devices did not include means for establishing the physical condition of the user as a variable in measuring calorie consumption.